THE IMMIGRATION OP PYRAMEIS ATALANTA. 19 



lanta in the early autumn because I like watching them (not to 

 " collect " them), and the autumn supply always seems to me to 

 be pretty constant, however few I may have seen in the spring. 

 Neither have I observed any numbers passing the Channel 

 Islands. 



At Alderney, in 1892, there was a perfect plague of Colias 

 edusa and Macroglossa stellatarum, but they remained in Alderney 

 the usual period, and did not leave the island. Will somebody 

 turn up the back files of the 'Entomologist' to see whether 1892 

 was a clouded yellow year in England or not? 



In Malta, P. atalanta is a very common insect. It appears 

 to have a succession of broods there. I had particularly 

 good opportunities of observing the insect in that island, as my 

 road to work every day led me past a spot where the insect bred 

 freely. I could always find it in one or other of its stages, and 

 when the perfect insects emerged I never noticed that they 

 moved far from the particular locality, neither did the numbers 

 of butterflies appear to diminish as though they migrated, 

 although Sicily and Italy are handy places for them to go to. 



Being very keen on sea-fishing and rowing, I spend many 

 days on the water, and at none of the islands where I have lived 

 have I seen any migration of butterflies, not even at Dover. 



Individual butterflies of course I have seen, but those I 

 always put down to chance ones, blown ofi" shore, or those that 

 have lost their way. One day, when steaming near Aden, a 

 sudden squall came off shore and brought with it hundreds of 

 locusts and many butterflies, which afforded amusement to the 

 children on deck, who enjoyed a butterfly and locust hunt at sea, 

 but nobody could say that either insect was migrating. One 

 often reads in accounts of tropical butterflies about the migrating 

 swarms of certain kinds, and especially species of Catopsilia 

 and Callidryas. Has anybody ever followed up a swarm, or had 

 a correspondent at the other end of the line of flight to say where 

 the butterflies ceased their wild career ? I take it the answer is 

 "No," because it is generally impossible in the tropics to go 

 straight across country, on account of the jungle. In Mauritius, 

 however, I once did see a migrating swarm — or rather thought 

 I did. It happened that one bright day when the south-east 

 trade wind had died away and a " Malagash " wind, i. e. a 

 westerly breeze from Madagascar, was blowing, that I went 

 butterfly hunting on the Trou-aux-Cerfs. Now a "Malagash" 

 wind only blows but very rarely, and when it does, the atmo- 

 sphere is very clear and bright but hot. The Trou-aux-Cerfs is 

 an extinct volcano, with a well-formed crater, perfectly circular, 

 filled with jungle, and on the outer sides grow small trees, 

 bushes, and lots of grass and Lantana. On arriving near the 

 top of the crater, and whilst collecting on the outside slope, I 

 noticed that there was an abnormal number of Atella phalantha 



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